Enter "5SQQ-5THA-ZFFV-7XEV" as a profile name. If you entered the code correctly, you will be able to re-enter an actual profile name after selecting "Done". When you begin the first level, you will have the BFG weapon. Note: Make sure to include the "-" symbol when entering the code (located next to the "!" symbol).
Alternately, enter one of the following profile names:
Successfully complete the game on the Normal or Hard difficulty setting to unlock silver weapons with infinite ammunition for that difficulty and any lower difficulty setting(s). Note: This does not include the Black Ops difficulty setting. You will always have silver weapons on that difficulty setting.
Successfully complete the game on the Black Ops difficulty setting to unlock the M16A2 (M16 with grenade launcher) for use on any difficulty setting.
Successfully complete the game on the Hard difficulty setting to unlock the Black Ops difficulty setting.
Immediately after shooting a round with the M16A2, switch weapons then quickly switch back and the grenade launcher will be reloaded.
When you are in the middle of putting a suppresser on your weapon and enemies appear, fire and the suppresser with be on with your weapon going instantly into firing position.
To get rid of the blur when you reload, press X to reload then immediately hold Square, or press X to reload then tap Triangle. To get rid of the blur with automatic reload, tap R1 and everything will become clear. Also when reloading the M16 MP5, etc. with X, some have longer reloads. You can stop a X reload and fire whatever is remaining in the magazine by pressing R1. You can also speed up reload by tapping R1.
Press R3 to zoom in x2 with the Sniper Rifle. When you are in this position, press D-pad Up as if you were changing the firing method of your weapon.
Try to shoot all enemies in the head. This usually brings them down in one shot and helps keep you alive. Since there is a smaller chance of you being killed by others if you do this, you can avoid having to repeat the level from the checkpoint and having to kill everyone again.
When reloading the Remington shotgun, the shells are red. However, sometimes the shells are black, and there are no black shotgun shells in the game.
Use destructive objects to your advantage to shock, hurt, or even kill enemies.
Head shots do not work on enemies with full body armor; just shoot. For enemies with shields, use grenades or RPGs. Or, get behind them and kill them by shooting them in the back. To kill shield enemies without using a grenade, shoot them on their left. You might take a little bit of damage, but it is worth it.
Shielded troopers will often stand beside large stone pillars in rooms (for example, in the "Tivliz Asylum" level). Do not shoot at the troopers; instead, shoot at the stone pillars above them. This will cause the stone to fall and crush them. If it does not appear to be working, you may need to aim higher.
The easiest way to kill RPG troopers is to wait until they fire a round (pop out then hides behind something). While they are reloading, shoot at his midsection. If successful, you will shoot and detonate the RPG he is trying to reload, blowing him up.
The M249 SAW, RPG (with at least four rounds), and at least two grenades (not those at the room entrance) are required for this trick. Do not enter the room because the door closes and it becomes difficult. Do not use any RPG rounds as you will need them later. Crouch at the door entrance and shoot the man with the flak armor in the back of the head. Then, shoot the others on the ground. To kill the men on the walkways, shoot the red object on the right side (on the walkway), then shoot the objects around the bottom of the left walkway; these will cause big explosions. When those men are dead, kill the next few in any order and do not forget the ones on the walkways. This will repeat until two appear on the walkway which is nearest to you. Kill them, then throw a grenade at each doorway at either end of the walkway. This should kill a few people (you will hear screams). If successful, more enemies will appear on the walkways and on the ground level. Enemies will keep appearing until the two bunkers open at the far end and RPG troopers. Do not worry, as only one RPG trooper appears at a time; there are three or four of them. Move back and wait for any last enemies or RPGs fired. Get out the way (or kill the enemies), then slowly go to the doorway until you can see a bunker. Take out your RPG and shoot it until the whole back wall explodes. Use this time to take out the last of the enemies. Watch out, as the RPG troopers will probably still be around, along with flak armored shotgun wielding men. This depends on how close they were to the back wall when it went up. Once everyone is dead and you have destroyed the safe on the walkway, go through one of the destroyed bunkers and complete the game. Sometimes this will not work out correctly and you will have to hide on the walkway (for example, if the door closes) and shoot them as they come.
The magnum with as many shots as possible, M249, and multiple grenades are required for this trick. Before you enter the room, crouch down in the archway and use the magnum to try to get as many head shots as possible and blow up explosives. After you are out of ammunition or when there are no any enemies remaining, take out the M249. Reload if needed, then run forward. When the shotgun and shielded enemies come out, keep moving and drop grenades at their feet. When they are cleared, shoot when possible and go up the stairs. Once up there, go into each room. Collect the armor and go into the other room. Once there, crouch down and take out the magnum (if you have ammunition), or use the M249 and wait for the enemies to come after you. After the enemies stop to appear for about two minutes, use the M249 and go down the stairs. There is a machine gun nest at the wall; subdue him and destroy the nest with grenades preferably, and enter it. When you do so, move around the corridor to complete the mission.
Once you get to the part where someone with a rocket launcher shoots at you from a ship tower, kill him then go down by the bottom of the ship. On the side of the steps, you will be asked to switch weapons for an RPG.
In the first border camp, there are houses on the right side of the road (as you enter the camp). Inside the houses are bulletin boards on the wall. Posted here are two pictures, which are the actors who portray Sgt. Kellar - Marty Papazian (unconfirmed likeness) and his interrogator, played by Paul Pape.
During the final battle there is a safe (one of the secondary objective items) on the left walkway. If you destroy the safe, a message similar to "'You have destroyed Secret Burnout Renders" will appear.
In the first mission, on any difficulty setting other than Easy, you can destroy Intel as a secondary objective. One of those Intel-containing laptops once destroyed holds information on an "Experimenting aircraft code named 'Aurora'." The "Aurora" is supposedly a real, yet secret, aircraft. Most of the Intel is real or based on real world information.
When you fire the AK47, the bullet casings are ejected from the wrong side of the gun. The bullet casings should come out of the right side, away from your face.